Copper and copper base alloys and methods of making the same



United States Patent COPPER AND COPPER BASE ALLOYS AND METHODS OF MAKING THE SAME Wilbur T. Bolkcom, Allison Park, and William E. Knapp, Pittsburgh, Pa., assignors to American Metallurgical Products Company, Pittsburgh, Pa., a partnership of Pennsylvania No Drawing. Application April 26, 1955 Serial No. 504,098

5 Claims. (Cl. 75-153) The present invention relates-to copper alloys and methods of making these alloys and particularly to copper and copper base alloys and methods of producing them by means of which the harmful effects of lead are overcome.

It is well known that the presence of lead in copper and in copper base alloys has very definite deleterious effects upon the alloys when present in excess of certain tolerance levels which vary somewhat from alloy to alloy depending upon its composition. For example, it is known that lead in copper and copper base wrought alloys impairs their hot workability to such a degree that above the lead tolerance level any commercial hot work is impossible. The maximum lead content which is tolerable in alloys of copper containing about 70% copper and 30% zinc is about .025%. In pure copper, the maximum tolerable lead content is about 005% and in copper alloys such as bronzes containing 90% copper the maximum tolerable lead is approximately .01%.

Many attempts have been made to overcome this impairment of quality in copper alloys caused by the presence of lead but without any real success. The only practical method currently being used for controlling lead in copper alloys is extreme scrap selectivity and, alternatively, dilution when high lead-containing raw materials are used. Neither of these alternatives is a satisfactory solution. Both are expensive and there is the ever present danger of exceeding the lead tolerance by a small amount suflicient to impair the quality of the copper alloy. We have found that copper alloys to which at least .0125% by weight of rare earth metals have been added are not subject to the deleterious effects caused by the presence of lead. Any of the rare earth elements including those having atomic numbers from No. 5 8 to No. 71, inclusive, of the periodic table are effective in our alloy and our method. In a similar fashion, any combination of these elements is satisfactory. We prefer to use misch metal as the source of rare earth metals, misch metal being a combination of the rare earth elements roughly proportionally in content to the occurrence of the rare earth metals in the natural ores. Similarly, any rare earth containing chemical which can be reduced to the metallic state in the copper melting bath simultaneously with its addition to the bath would be satisfactory in our method but we do not prefer this type of addition.

The surprising effect of our invention on copper containing alloys is illustrated in the following tables in which rare earth metals in the form of misch metal were added to a common brass and to substantially pure copper:

In Table 1, we have tabulated the effect of varying rare earth additions on a typical 70% copper-30% zinc brass with varying lead content.

Table 1 Percent Percent Lead Lead Rare Content Content Earth Percent Percent Batch 1 Before "After Addition Rare Scrap Number Rare Rare Per Ton Earth 7 Loss Earth Earth of Brass, Added Metal Metal pound Addition Addition 010 010 M 0. 0125 1. 06 010 010 56 0. 025 1. 09 010 007 1 0.05 i 1. 03 010 003 2 0. 1 l. 05 010 010 0 0 1. 11 024 023 94 0.0125 2. 95 024 020 6 0. 025 1. 24 024 016 1 0.05 1. 15 .024 013 2 0.1 1. 13 024 024 0 0 31 05 046 A 0. 0125 14. 8 05 042 0.025 6. 44 05 036 1 0. 05 1. 9 05 021 2 0. 1 l. 1 05 05. 0 I 0 100 1 085 54 0. 0125 28:7 1 07 K 0. 025 12.6 1 051 1 0. 05 3. 8 1 039 2 0. 1 1. 78 1 1 0 0 100 In the following Table 2 we have tabulated the effect of varying rare earth additions .on 99.9% pure copper with varying amounts of lead.

Table 2 Percent Percent Lead Lead Rare Content Content Earth Percent Percent Batch Before After Addition Rare Scrap Number Rare Rare Per Ton Earth Loss Earth Earth of Copper, Added Metal Metal pound Addition Addition 001 001 0. 025 47 001 001 0 0 51 004 004 $4 0. 0125 1. 20 004 003 5 0. 025 61 004 003 1 0. 05 58 004 .002 2 0. l 56 004 004 0 0 10 008 008 $4 0. 0125 11. 1 008 006 0. 025 6. 9 008 005 l 0. 05 1. 2 008 003 2 0. 1 53 008 008 0 0 27 02 018 M 0. 0125 34. 0 02 014 14 0. 025 3. 5 02 011 1 0. 05 l. 6 02 007 2 0. 1 55 02 02 0 O 90 It is readily apparent from a comparison of the percent scrap loss in the foregoing tables that the addition of rare earth metals to copper and copper alloys containing lead results in a marked reduction in the scrap losses. This is strikingly illustrated in those cases where the lead content is highest as in the case of the 162 and 17Z series of the -30 brass and the 10X series of pure copper where in the case of 70-30 brass the scrap loss is reduced from 10% to less than 2% by the addition of two pounds of rare earth metal and in the case of pure copper the scrap loss is reduced from to slightly over a half of a percent.

We believe that a portion of the lead in copper and copper base alloys is physically removed by the addition of rare earth metals to the molten metals. Careful tests indicate, however, that it is not necessary for the lead to be physically removed for the rare earth metals to be effective in neutralizing harmful effects. A study of shortness.

' I ables 1 and 2 confirms our'beliefs in these matters. We

also believe" that tli'e'rare' earth metals fdrm"'extremely high melting point compounds with the lead thereby preventing the lead from coating the copper and copper alloy crystallities upon solidification, and thereby creating hot While our researches have indicated the truth of our beliefs as stated above, we do not wish to be bound by these beliefs which are simply our explanation of the striking and unusual phenomenon which we have discovered. Accordingly, while we have illustrated and described certain preferred embodiments of our invention, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

We claim:

1. A method of eliminating hot shortness in copper and copper alloys having lead incidental to its manufacture as an impurity in ordinary amounts, comprising the steps of reducing said alloys to the molten state, adding to said alloys while in the molten state atleast 50% by weight as much rare earth metal'as'lead originally present and solidifying the resulting molten mass.

2. A method of eliminating hot shortness in lead-comtaining copper and copper alloys, the lead being present combinewiththe lead and solidifying the resulting molten mass, the said rare earth metal being present in an amount equal to 'at' least 50% of the leadconten't' originally present.

3. A method of eliminating hot shortness in copper and copper alloys having lead incidental to its manufacture as in impurity in ordinary amounts comprising the steps of reducing said alloys to the molten state, adding to said alloys while in the molten states at least 50% by weight as much rare earth metals as lead originally present but not less than 0.0125 and solidifying the resulting molten mass.

4. A hot worked copper alloy-containing up to about T 0.1% lead and 'a rare earth metal in an amount suflicient to'stoichiometrically combinewith substantially all of the lead in the alloy.

5. A hot worked copper alloy containing lead, said lead being present in an amount up to about 0.1% and also containing rare earth metals, the said rare earth metal being present in an amount equal to at least about of the lead content.

OTHER REFERENCES The Foundry,Iuly 1, 192 2, pages 542-544.

I 7 Evans Aug. 29, 1944 12,892,733 Bungardt Aug. 13,1957 

1. A METHOD OF ELIMINATING HOT SHORTNESS IN COPPER AND COPPER ALLOYS HAVING LEAD INCIDENTAL TO ITS MANUFACTURE AS AN IMPURITY IN ORDINARY AMOUNTS, COMPRISING THE STEPS OF REDUCING SAID ALLOYS TO THE MOLTEN STATE, ADDING TO SAID ALLOYS WHILE IN THE MOLTEN STATE AT LEAST 50% BY WEIGHT AS MUCH RARE EARTH METAL AS LEAD ORIGINALLY PRESENT AND SOLIDIFYING THE RESULTING MOLTEN MASS. 